Breather assemblies for axle housings, transmission housings and other housings having rotatable elements therein and/or non-rotatable elements therein are well known for venting the interior of the housing to the atmosphere. The operation of the rotatable elements within these housings typically generates a certain amount of heat. The lubricant within the housings, used to facilitate the rotation of the rotatable elements, receives this heat. The heat increases the vapor pressure of the lubricant and the air, or gas, within the housing. If this pressure is not expelled from the housing, the lubricant will be undesirably forced through whatever sealing means are in place.
Various breather assemblies for the housings described above have been patented. For example, U.S. Pat. No. 2,880,744 provides for a housing vent that includes a tubular vent body with a separate baffle disk mounted within the vent body.
U.S. Pat. No. 3,145,582 teaches a breather assembly having a single pair of baffle plates therein. The baffle plates are designed to collect any lubricant spray that may enter the breather and return to the case. The plates are also designed to also allow gas to escape from the case. The baffle plates have gas openings that are not aligned with one another to reduce the likelihood that fluid will go through both and escape through the assembly. The plates are described and depicted as located within a stand pipe of the assembly.
U.S. Pat. No. 4,794,942 teaches an air breather plug assembly having a cylindrical plug body and a cup-shaped baffle plate fixedly coupled within an inner end portion of the plug body. The baffle plate has a pair of radially spaced semi-circular slots formed therein. The slots are designed to permit only a small amount of lubricant into the plug body. A resilient seal member, located above the baffle plate, has a slit that opens only if the pressure within the assembly exceeds a pre-determined amount. The resiliency of the seal member generally keeps the slit closed, thus maintaining the small amount of lubricant located within the plug body.
The above-described breather assemblies suffer from several disadvantages. First, the prior art breather assemblies have to be located above the lubricant level in the housing. Second, these breather assemblies have to be located at specific angles with respect to the housings to function properly. Third, despite their designs, the breather assemblies are known to allow lubricant, sometimes a significant quantity, to escape from the housing. Fourth, the prior art designs lack means to prevent a lubricant seal from forming against the base of the breather assembly thus blocking air from entering into and escaping from the housing. In light of the disadvantages of the prior art, a breather system that can be installed anywhere on a housing, at any angle, that significantly reduces, or prevents, lubricant from escaping from the housing, yet allows air into and out of the housing, is needed.